Biomedical subjects
Publications and source records attributed to R M Barr.
A 68-year-old man with polycythemia rubra vera developed gradually progressive paraparesis followed by an acute, painless paraplegia. Extradural thoracic spinal cord compression was found to be secondary to extramedullary hematopoiesis (EH). The neurological complications of EH are reviewed.
When polymorphonuclear leucocytes (PMN) elicited in mice were infected with Mycobacterium microti or Mycobacterium lepraemurium, phagosome-lysosome fusion occurred with both species. This contrasts with the situation in macrophages where phagosome-lysosome fusion is inhibited by M. microti but not M. lepraemurium. No evidence was found for killing of M. microti or M. lepraemurium when the bacteria were isolated from PMN and their viability tested in cell-free medium or macrophages.
The efficacy of measuring the transferrin saturation and the serum ferritin concentration to detect iron deficiency was determined under routine conditions in a general hospital. The tests were performed on 100 adult patients who consecutively underwent bone marrow aspiration for the appraisal of a wide range of clinical conditions. The absence of stainable reticuloendothelial iron in smears of the aspirate was used as the benchmark of iron deficiency. Of the 86 patients who were anemic 19 lacked hemosiderin in the bone marrow. The percentage of patients with iron deficiency who were correctly classified by the tests (i.e., the tests' sensitivity) was 84% for the transferrin saturation and 79% for the serum ferritin concentration, and the percentage of patients free of iron deficiency who were correctly classified by the tests (i.e., the tests' specificity) was 63% and 96% respectively. The predictive value of an abnormal (positive) result for the detection of iron deficiency was 39% for the transferrin saturation and 83% for the serum ferritin concentration, whereas the predictive value of a normal or high (negative) result for the exclusion of iron deficiency was 93% and 94% respectively. Measurement of the serum ferritin concentration was superior to measurement of the transferrin saturation only in its specificity. The former is of particular value in clinical settings where the prevalence of iron deficiency is low and conditions that increase the serum ferritin concentration out of proportion to the size of the body iron stores are infrequent.
The incorporation of [1-14C]mannose into hamster liver glycolipids and glycoproteins was studied in normal and vitamin A-depleted hamsters. Severly (25% weight loss) and mildly (no weight loss) deficient animals were compared to vitamin A-fed controls. The incorporation of [14C]mannose into glycolipids and glycoproteins decreased in mild and severe vitamin A deficiency by 63-90% compared to vitamin A-fed animals. These results were essentially the same whether expressed per g of wet liver, per DNA or per protein. The size of the pools of mannose, glucose and galactose and their specific radioactivity in liver were determined by gas-liquid chromatography of the boronates of the hexitols (Eisenberg, Jr, F. (1972) Methods Enzymol. XXVIIIB, 168-178) in normal and vitamin A-deficient conditions. It was found that the amount of free hexoses per g of liver was very similar in normal and vitamin A-deficient conditions. The specific radioactivities for mannose and glucose were greater in vitamin A deficiency, thus excluding the possibility that the observed severe decrease in glycopeptide and glycolipid synthesis is a reflection of a similar decrease in the specific radioactivity of the precursor pools. Quantitation of mannose in glycoprotein showed a 79% decrease in vitamin A deficiency. Specific radioactivity of mannose in glycoproteins, 20 min after injection of the label, was 187 dpm/mug of mannose in the normal and 48 kpm/mug of mannose in the vitamin A-deficient livers. It is concluded that vitamin A is necessary for the biosynthesis of liver mannose-containing glycoproteins and glycolipids.
Three urinary excretion tests of vitamin B12 absorption were done in 12 patients with classic pernicious anemia. The 24-hour urinary excretion of radioactivity was 2.1% +/- 0.7% (mean +/- SEM) of the ingested dose of cyanocobalamin-57 Co. When cyanocobalamin-57 Co was mixed with hog intrinsic factor in water, excretion increased to 15.6% +/- 1.6%. When cyanocobalamin-57 Co and intrinsic factor were given in two separate capsules, which is now a frequent practice, excretion was 9.5% +/- 2.2%. In 6 patients, use of the results obtained with capsules could have led to an incorrect diagnosis. When cyanocobalamin-57 Co and intrinsic factor are given in separate capsules, binding of radioactive vitamin to intrinsic factor may be incomplete due to inadequate mixing in the stomach or to binding of intrinsic factor to blocking antibody in the gastric juice. The classic technique in which intrinsic factor and cyanocobalamin-57 Co are mixed in water before administration should be used.
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A polyprenol complex of Aspergillus niger was shown, by using spectrometric methods, to consist of a family of exo-methylene-hexahydroprenols that contain between 18 and 24 isoprene residues per molecule. Each prenol contains two trans residues, three saturated residues (alpha, omega and psi) and an exo-methylene substituent on the carbon atom beta to the isopropyl group in each omega-residue. The ubiquinone complex consisted of 90% ubiquinone-9, 9% ubiquinone-8 and 1% ubiquinone-10. The amount of polyprenol complex present reached a maximum of 1.7mg/culture bottle after 9-10 days of growth, coincident with the maximum weight of mycelium. The amount of ergosterol (10mg/culture bottle) and ubiquinone (1mg/culture bottle) reached a peak at 8 days. By the 13th day of growth the yield of ergosterol had fallen by 20% and that of ubiquinone by 85%. A study of the incorporation of [2-(14)C]mevalonate over different time-intervals confirmed that there was a slow turnover of prenol, a more rapid turnover of ergosterol and a very rapid turnover of ubiquinone. At any one time each member of the prenol complex had essentially the same specific radioactivity as other members of the complex. A similar conclusion was made about the ubiquinone mixture. Just over half of the polyprenol present was esterified to fatty acids. Subcellular fractionation studies indicated that the unesterified prenol is associated primarily with a mitochondrial fraction, whereas the ester is more widely distributed.
Growth of Aspergillus niger in the presence of [2-(14)C]mevalonate and (32)P(i) led to the formation of a lipid, containing (14)C (0.14% of dose) and (32)P (0.009% of dose), that had chromatographic properties identical with those of exo-methylene-hexahydropolyprenol phosphate. When a particulate enzyme preparation from the thallus of A. niger was incubated with GDP-[(14)C]mannose, the main radioactive products were mannose 1-phosphate (57% of products) and mannose (18%). In addition radioactive mannan (8%) and a mannolipid (2%) were formed. The latter was identified as exo-methylene-hexahydropolyprenol phosphate mannose on the basis of its chromatographic properties, acid lability and on the increase in formation of the mannolipid when the phosphate of exo-methylene-hexahydropolyprenols was added to the incubation mixture. The phosphates of ficaprenols and cetyl alcohol caused no corresponding increase. These observations are interpreted as evidence that the thallus of A. niger contains a mannose transferase that uses the phosphate of exo-methylene-hexahydropolyprenols as an acceptor. This situation is discussed in the light of the analogous involvement of a prenol phosphate mannose as an intermediate in the biosynthesis of bacterial wall mannan.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Investigation of the serum of three patients with positive antibody detection tests demonstrated the cause in each to be an antibody against chloramphenicol, a bacteriostatic agent used in commercial red blood cell reagents. Washing of these red cells prior to use prevented agglutination. All three examples of anti-chloramphenicol antibody were IgM and were in low titer when tested at room temperature and 37 C in saline. Two of the antibodies bound complement. The possibility of an antibody to an ingredient of the commercial preservative solution should be considered if problems are encountered in tests with unwashed commercial red blood cell reagents.